Process control systems typically include one or more process controllers communicatively coupled to at least one host or operator workstation and to one or more field devices via analog, digital or combined analog/digital buses. The field devices, which may be, for example, device controllers, valves, valve positioners, switches and transmitters (e.g., temperature, pressure and flow rate sensors), perform functions within the process control system such as opening or closing valves and measuring process parameters.
Process control systems used to manufacture important products (e.g., human pharmaceuticals, animal pharmaceuticals, biological products, etc.) have high quality (e.g., purity, reliability, consistency, etc.) standards and are regulated by government agencies (e.g. the Food and Drug Administration, the U.S. Department of Health and Human Services, etc.). These process control systems are recommended and may soon be required by FDA to provide statistical data that shows the product quality is consistently meeting quality specifications and the process is running in a state of control
Wherever possible, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts.